Henderson Hasselbalch
Calculator
Results
- pH
- 4.76
- Base to acid ratio
- 1
- pOH
- 9.24
Chemistry results
| pH | 4.76 |
| Base to acid ratio | 1 |
| pOH | 9.24 |
formula-map diagram
- pH
- 4.76
- Base to acid ratio
- 1
- pOH
- 9.24
Formula breakdown
Formula
pH = pKa + log₁₀([A⁻] ÷ [HA])= 4.76
Note
Simplified model: these results assume ideal behaviour (ideal gases, dilute solutions, complete reactions) and standard textbook constants. Real laboratory values vary with temperature, pressure, purity and activity coefficients. Do not rely on this for safety-critical or analytical work.
More in Chemistry
See all →Frequently asked questions
What does the Henderson-Hasselbalch equation calculate?+
It calculates the pH of a buffer solution from the acid dissociation constant and the ratio of conjugate base to weak acid concentrations: pH = pKa + log10([A-]/[HA]). It's the standard tool for designing and analyzing buffer solutions.
What happens to the pH when the acid and conjugate base concentrations are equal?+
When [A-] equals [HA], the log term becomes log(1) = 0, so the buffer's pH simply equals its pKa. This is why pKa is often described as the pH at which a buffer has its maximum buffering capacity.
Why do buffers resist changes in pH?+
A buffer contains both a weak acid and its conjugate base, so added H+ ions are absorbed by the conjugate base while added OH- ions are neutralized by the weak acid, keeping the [A-]/[HA] ratio — and thus the pH — relatively stable. This resistance only works within a limited range, roughly pKa ± 1.
What's the effective buffering range of a given buffer system?+
A buffer works best within about one pH unit of its pKa (pKa ± 1), because outside that range one of the two components becomes too scarce to neutralize added acid or base effectively. Choosing a buffer means picking an acid whose pKa is close to your target pH.
Does the Henderson-Hasselbalch equation work for strong acids and bases?+
No, it's derived specifically for weak acid/conjugate base equilibria and assumes the acid is only partially dissociated; strong acids and bases dissociate completely, so their pH is calculated directly from concentration instead.